Railway Access

To get access to the Railway Station you need to do two requirements first:

Get a ticket: Search in Saffron for a house with a purple rooftop. The Copycat wants a Pokedoll, which you get from the Pokemon Fanclub in Vermilion. Bring her the doll to get the ticket.

POWERPLANT

Go to the Powerplant below Route 10 and defeat the burglars. To get this quest, go talk to Hank, who asks you to scare away the burglars. After completing this quest, the railway station has power again.

Another task awaits you in the underground here you can find the guide.